Edit: Not entirely sure what I should be looking for. Checked the voltage settings and such, but I can't edit anything for the 550ti since I can't plug it in without the monitor not working, which is an old hp w17e.
It will be more of a case as you forgot to plug in the extra 8 or 6 pin 12v power connector located next to the Cpu socket of the board from the power supply unit.
Open up the case have a look in make sure you connected that power lead.
It provides extra power to the Cpu, but also from the board provides a bit of extra power to the Pci-e graphics slot of the board.
This will cause a black screen and the fans spinning but no post of the computer.
Also if the graphics card requires extra power, connect the power plug from the psu that says Pci-e 12v to the back edge of the card.
You'll have to find a DVI cable instead of a VGA cable because if you have a graphics card installed it will no longer display through the motherboard. Until you do find one you could unplug the GPU and put it back in it's original box.
Some GPU even come with adapters so check the original packaging. Another spot to look would be the monitors box. Hopefully you didn't throw all this stuff out yet.
The monitor is around 5 years old so I do not have that box anymore, I don't think it had a DVI cable anyways. I still have everything from the PC build stacked up in the corner of the room, but I didn't see a cable in the graphics card box either so I'll just get one when I buy a wireless adapter later today. I don't have any internet access on it so I can't do anything for updating really.
Thank you for saving me money thinking I need to buy a stronger PSU.